New Physics

Etu Malku said:
Do you think the universe will reach an expansion point where it stops, then begins to retract again?
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The scientific consensus, as I understand it, is that with the recent discovery of an acceleration of the expansion of the universe, the "big crunch" idea of retraction has been largely abandoned, as dark energy seems too strong for gravitational force to overcome in order to drive the retraction.

Now the likely scenarios for the fate of our expanding universe are the "big chill" and the "big rip", or possibly the heat death that Radar has mentioned.

But there are also some theories that dark energy may be some variation on quintessence, the old Greek notion of a fifth element. Quintessence, if it exists, could cause dark energy to appear and disappear over time; in which case who knows what the fate of our universe would be.

These are truly exciting times to follow physics and astronomy, particularly with the massive E-ELT telescope slated for construction in Chile. It will be four times larger than any other telescope, gathering 16 times the light of any existing telescope! I have a 12" dobsonian reflector telescope to probe the dark Iowa skies and can only drool over those big boys...
 
I think this is absolutely fabulous conversation (if I knew wtf I was reading lol) . . . I get it to a degree. I'm just gonna follow along and throw in some stupid metaphysical question now & then
 
Etu Malku said:
I have often imagined the universe as being inside of a ball and the inside wall is a mirror of infinite reflection, depending on how much I am conscious of will determine how much I see/understand.

Are there any scientific platforms that come close to this concept?
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You're supposed to look outside the telescope, not inside it. :p
 
Dream said:
Do we know the point that we are traveling away from and how fast we're going relative to that?
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We don't know the point we're traveling away from, as the observable universe doesn't have a "hollowed-out" center as you might expect from a Big Bang explosion, i.e. there is no "center" of the observable universe at all. And we can't see part of the universe so who know's what's going on there or how much we can't see.

But we do know how fast we're going relative to everything else. Hubble's Law can calculate how fast something is traveling away from us depending how far away it is:

v = H0D

with H0 being Hubble's Constant which is being re-calculated with nearly every deep space mission and is thought to be approximately 70 (km/s)/Mpc

So, for every Mpc (units analogous to million light years) distant from us, an object has a velocity of 70 km/s away from us. So, the farther away, the faster away from us it's moving. And if VERY far away, moving away from us so fast that we can't even see the light coming from it.

hubflo.jpg
 
radarmark said:
I am no fan of "many-worlds" or "many-minds" theory. I believe that the "collapse of the wavefunction" is nothing more than what an "observation" was in classical theory. Real simple hard-core Copenhagen interpretation.
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We really need to get to grips with Eriugena!

Or rather ... I really need to get to grips with him, and then you'll suffer a barrage of questions!

God bless,

Thomas
 
Mathematically (which is really all we have to go by) the results (what we observe) in Copenhagen, Bohmian, many-worlds, and many-minds are the same. They would have to be for an interpretation to be consistent with the evidence.

Pax et amore omnia vincunt!
 
radarmark said:
I believe the universe to be in a continual cycle. This is based on a very, very complicated "quantum information" theory the best parallel in the popular literature is the Baum–Frampton model given in last reference.
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OK, looked up Baum-Frampton, so according to that theory just before a "big rip" due to universe expansion/acceleration the universe instead contracts and possibly splits into multiple universes. So, do you believe multiple universes exist now? i.e. has this "continual cycle" happened before?

Baum-Frampton sounds similar to the ancient Hindu belief that the universe is constantly destroyed and then recreated in an endless cycle.

But it seems to me that any cyclical model of universe creation goes against the 2nd Law of Thermodynamics (entropy always increases), would you agree with that statement?

Fun discussion!
 
You got it, but I do not believe in multiple universes (via Ockham's razor). As for 2nd law, you have to also make your equations consistent with gravity (see Penrose's new book) and phyaics as information theory (see the Zurek work at Sana Fe Institute).

Think about th3e big bang. On the thermo side, the moment would have been one of total equilibrium... all that mnass/energy interconnected in a real big quantum superposition at the singularity. No gravitational, EM, weak, strong forces--just some real big megaforce. so....

The temperature was in equilibrium and the universe was therfore it was a state of maximum entropy! Hyperinflation (during the first moments) and "freezing out of forces" (otherwise known as symmetry breaking) are just ways to explain how a maximum entropy state got to a low entropy state. P.S. they would work in negative time (see Penrose's "Cycles of Time") so the entropy returns to original conditions.

I know that is WIERD! But black hole-white hole twistor theory or some quantum loop gravities allow it (per Penrose, I have not, make that dared not, try the equations... twistors can be seen as tensors of tensors and really take some geometry skills I never developed, I am not sure if anyone ever did before Penrose, but those who tackle it like those that tackle M-Sting etc swear it is consistent).

BOTTOM LINE: Somehow the symmetry breaking allowing gravitational forces to exist at very early times probably vastly decreased the entropy after the singularity. Similarly in the rip (good analogy, another is white-hole amalgamation) gravity ceasing would dynamically increase entropy during a big crush to allow the next big bang. Yes, a Hindu-like conception. I find it more beautiful and symmetric than the heat-death, big chill or big rip theories. Maybe someday we will know, but do not hold yer breath!
 
The more I learn about our universe the wierder it seems! I can barely wrap my mind around the current theories out there; but the "truth" is probably wierd beyond our wildest imaginations... I'm still holding out for the possibility of time travel :)

Radar, once this big-ass, high-elevation telescope is operational in Chile in a few more years, what measurements would you want them to take?

i.e. what astronomical data could we reasonably collect that would help us to refine our knowledge of dark energy/dark matter and other modern mysteries of the universe?
 
Iowaguy said:
We don't know the point we're traveling away from, as the observable universe doesn't have a "hollowed-out" center as you might expect from a Big Bang explosion, i.e. there is no "center" of the observable universe at all. And we can't see part of the universe so who know's what's going on there or how much we can't see.

But we do know how fast we're going relative to everything else. Hubble's Law can calculate how fast something is traveling away from us depending how far away it is:

v = H0D

with H0 being Hubble's Constant which is being re-calculated with nearly every deep space mission and is thought to be approximately 70 (km/s)/Mpc

So, for every Mpc (units analogous to million light years) distant from us, an object has a velocity of 70 km/s away from us. So, the farther away, the faster away from us it's moving. And if VERY far away, moving away from us so fast that we can't even see the light coming from it.
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So then I am the center of the universe, after all.
 
Dream said:
You should call it the 'Somebody must have farted' theory.
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Yes, that does have a better ring to it than Hubble's Law!

One cool thing about Hubble's Law that I forgot to mention is that, from any point in the observable universe, one will experience the same phenomena, that is, everything is moving away from you in all directions. So, no matter from which point you are in the universe, you will have the illusion that you are the center of the universe.

Similar to a rising loaf of raisin bread, where the bread is the universe & the raisins are the stars/planets:

bread.jpg
 
Numerous questions are popping up from this.

1. Its been pointed out that the expansion is an energy-less expansion. Does this mean that matter is thinning?

2. Has gravity been modeled, that you know of, as an inertial effect of the expansion, like a dragging effect of it?

3. Assume matter is a condensed form of energy. Does that mean matter becomes more solid when it gains kinetic energy?

4. If you could run into a wall an infinite number of times, supposedly there is a probability to phase through it with no impact. Do you think this may be an effect of the thinning? If so, will it increase and turn us into ghosts?

5. Is there a probability that matter could 'Phase' to a great distance or to another time at random? If so, will this increase with the thinning and will it decrease?

6. We cannot create energy or matter but can see its entropy increase, and the universe appears to be expanding. Some feel the universe goes through cycles or has a beginning, but what if I suggested the universe had been expanding forever and always will. Are there observations that oppose this idea or some solid principle it would break?

7. Is it possible for the universe to appear to Hubble to expand but yet be shrinking relative to some other universe.

8. Or perhaps could the appearance of expansion be an observational distortion due to shrinking?
 
:D
Dream said:
1. Its been pointed out that the expansion is an energy-less expansion. Does this mean that matter is thinning?
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If the volume of the universe is expanding and no new matter is being created then the density of matter is decreasing. The standard Big Bang Theory (SBBT) does not include matter being created, so in SBBT, yes.

Dream said:
2. Has gravity been modeled, that you know of, as an inertial effect of the expansion, like a dragging effect of it?
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Two totally different things... Gravity is the impact of the metric (a fancy physicist term for how distance is measured. In GRT (General Relativity Theory), time is the fourth dimension, so the entire metric (including time) is expanding. This is ignored in SBBT, to what effect? dunno. How do you rationally discuss the expansion of time in time? Anyway all time is local and relative, so you can safely ignore this aspect (we think) and the impact is shown elsewhere.

The problem is that Gravity is a result of the metric. Put in physicsese "gravity is the result of the curvature of the spacetime metric as measured by the metric tensor". Take a roulette wheel ball, the croupier spins it in the opposite direction from the wheel's motion along an inwardly curved surface. The ball gradually sinks along the wall of the surface (due to gravity). The ball is any mass (including energy) and the force of gravity is, well, the force of gravity changing the location of the ball to an outside observer.

The expansion is decoupled from gravity in both SBBT and GRT. However, if there is a local change in the metric tensor, then gravity increases or decreases. The effects (to my limited knowledge) would be a challenge to measure (if there) because the universe is so big and the rate of expansion and the gravitational effects are so small.

Conversely, in a local sense (Galactic cluster, the Milky Way, or the solar system) gravity is so much larger than any possible effects that they (again) would be (at this time) unmeasureable.

Dream said:
3. Assume matter is a condensed form of energy. Does that mean matter becomes more solid when it gains kinetic energy?
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No, the trade between matter and energy is so one-sided (remember mass equals energy times the speed of light squared) that, again, we will (probably) never know. At this scale, it is Quantum Mechanics that comes into play. For instance, take a uranium nuclei that splits into, say, krypton and barium, the mass afterwards is less but the average density (we cannot say anything about the actual density because nuclei are quantum-sized things) is the same. The notion of “solid” applied to this process does not compute.

Dream said:
4. If you could run into a wall an infinite number of times, supposedly there is a probability to phase through it with no impact. Do you think this may be an effect of the thinning? If so, will it increase and turn us into ghosts?
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There is just such a process (even without expansion) called the tunneling effect (see http://en.wikipedia.org/wiki/Quantum_tunnelling). Even for an average joe or jane, there is a small (one divided by about the age of the universe) probability that they would simply “pass through”. This has nothing to do with expansion, because like I said above, the expansion is overwhelmed by the local force of gravity.

Dream said:
5. Is there a probability that matter could 'Phase' to a great distance or to another time at random? If so, will this increase with the thinning and will it decrease?
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Now that is very interesting. One counter argument to the SBBT is that “dark energy” (about 75% of all the mass energy in the universe) could “decay” into real matter or anti-matter (this is mere speculation and the “decay” is not meant to mean actual; decay but “in a process similar to decay”) thereby bringing about my favorite cosmology, cyclic big bang theory with big bangs followed by big crunches for eternity (I am no sting theorist, but this is where brane and superstring theory go).

Dream said:
6. We cannot create energy or matter but can see its entropy increase, and the universe appears to be expanding. Some feel the universe goes through cycles or has a beginning, but what if I suggested the universe had been expanding forever and always will. Are there observations that oppose this idea or some solid principle it would break?
Click to expand...
Well, yeah, the SBBT (standard theory) assumes a lot. These assumptions are what “stack the deck” to make infinite expansion work. See, we assume “dark matter” and “dark energy” to account for what we see, then what we see is a function of what we assumed. Penrose has a really, really good rap in “Cycles of Time” (check it out and just skin the math and geometry). The problem with SBBT is that the big bang must be a moment of maximum entropy because everything is a singularity. Hyperinflation (inflation of expansion billions of times larger than what we measure now) in the early moments of the universe has to be assumed to account for this and cosmic background radiation. But, as he proves, this need not be the case (he is not a supporter of SBBT). There are only one or two others out there looking at the kind of questions you raise in this and the previous one.

Dream said:
7. Is it possible for the universe to appear to Hubble to expand but yet be shrinking relative to some other universe.
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Again, you get a metaphysical brownie point. But (if quantum and relativity are correct) we can never know this, never have communication with said sister universe.

Dream said:
8. Or perhaps could the appearance of expansion be an observational distortion due to shrinking?
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Yet another metaphysical brownie point. But what it would take is a “tricking” of the Hubble constant. Why would red shift be apparent when the cause is not expansion. The Hoyle-Gold-Bondi “steady state universe” used interstellar dust. But then you have to overcome the cosmic microwave background (this is what “killed” steady-state). This, like my favorite relativity topic, Whitehead’s Relativity, are complex and big problems (to show how steady-state could explain CMB or how Whitehead could be reformulated to be consistent with the Wills’ data) will, I am afraid never be looked at seriously.:D

Hope that hepls! Pax et amore omnia vincunt!
 
Dream said:
what if I suggested the universe had been expanding forever and always will. Are there observations that oppose this idea or some solid principle it would break?
Click to expand...

This would go against Hubble's Law, which says that the universe is expanding and calculates the velocity of objects away from an observer depending on their distance. This would also go against the cosmic background radiation observations/measurements (which was predicted by Einstein's theories and later confirmed by experiment after his death).

Hubble's Law, extrapolated backwards in time, gives an estimate of when the big bang took place (i.e. the age of the universe). So, Hubble's Law predicts a "start time" to the expanding universe. In fact, the concept of "big bang" didn't exist until Hubble discovered that the universe is expanding. Until then most scientists (including Einstein) believed the universe was static.

The "always will expand" part is a tougher question as there are many physicists that believe in a big crunch (expansion will stop) and many that believe in a big rip or big chill (expanding forever). As we learn more about dark energy and dark matter hopefully we can refine our theories about the ultimate fate of our universe, though I doubt we will ever know with much certainty.
 
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